1. Field of the Invention
The invention relates to a tachograph, in particular a digital tachograph, a toll onboard unit for detection of road usage fees, a display instrument, and to a system having such items, in particular for motor vehicles.
2. Prior Art
Vehicles are increasingly being equipped with electronic controllers for detection and evaluation of sensor signals, and/or for controlling vehicle functions. Some of these controllers are coupled to one another via a vehicle data bus which, for example, is in the form of a “Controller Area Network”, or CAN for short. Controllers transmit messages via this vehicle data bus, which messages can be received and evaluated by other controllers which are connected to this vehicle data bus. Goods vehicles are equipped with a tachograph and, to an increasing extent, with a toll onboard unit. In the future, passenger vehicles may also be required to be equipped with a tachograph and a toll onboard unit.